Insulators are commonly employed for supporting high voltage electrical components and maintaining those components in a spaced relationship relative to other structures and the ground. The supporting structures are normally maintained at or very close to ground potential. For special applications, the supporting structures may be energized at a higher electrical potential. One insulator is disclosed in U.S. Pat. No. 3,898,372 to Kalb. This insulator includes a central rod of insulating material, such as fiberglass. The ends of the rod include coupling members for attaching the rod to transmission lines and other components and to supporting structures. The rod is surrounded by a series of weathersheds of a rubber-like polymeric material, for example, EPM. The weathersheds are placed end to end along the rod to form a long external surface path. A dielectric material fills spaces between the weathersheds and the insulator central rod to fill any voids between the rod and the weathersheds and to exclude contaminants and moisture which might otherwise form a conductive path. Another insulator is disclosed in U.S. Pat. No. 4,610,033 to Fox. This insulator provides a channel for an optical fiber extending through the insulator between housings at opposite ends of the weathersheds. The optical fiber or fibers can form a communication path between a sensor on an electrical device and a ground location, or form a communication link between two ground locations with a fiber extending along a transmission line. The optical fiber is positioned in an open groove in a support rod of the insulator, such that the optical fiber is exposed to and susceptible to damage and cannot be repaired without replacing the entire insulator.
While these insulators are effective for their intended purposes, they do not satisfy all operational requirements. Specifically, these known insulators cannot work effectively where forced cooling is desired or necessary.
The power handling capacity of high voltage electrical equipment is usually limited by the operating temperature of the conductors and dielectric materials of the apparatus. Power ratings can often be increased significantly by cooling critical components. Closed path circulating liquid cooling systems are particularly effective, although open path cooling systems can also be used.
Thus, a need has developed for providing forced cooling systems conveying cooling fluid for outdoor high voltage electrical equipment. Additionally, a need has developed for an insulator with an optical fiber channel which better protects and permits replacement or repair of the optical fiber.